There is an "overwhelming temptation" for growers of medical marijuana to supplement their income under the current system by selling extra pot, the RCMP says.

Police investigations have revealed various abuses of the federal medical marijuana program, including trafficking for personal gain, violent theft of homegrown pot and involvement of organized crime, RCMP Cpl. Shane Holmquist says in an affidavit filed in the Federal Court of Canada.

Health Canada plans a revamp of the medical marijuana system — in part due to concerns about criminal infiltration.

Under the existing program, to be phased out by April 1, people are issued licences to grow marijuana for their personal use to help ease the symptoms of painful conditions.

Several British Columbia residents with licences to grow their own pot are asking the Federal Court for an injunction that would allow them to continue doing so.

They argue the proposed new system, under which only licensed producers could grow marijuana for distribution to approved patients by mail, would deny them a safe supply tailored to their needs at an affordable price.

Under the current regime, just over 30,000 people have a licence from Health Canada to grow marijuana for themselves or for another person. More than half of them are in B.C.

In his court submission, requested by the federal government as part of its defence, Holmquist says he has seen numerous instances of licensees trafficking marijuana they grow — sometimes through cultivation of oversized "monster" plants.

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In one case, a grower stated one room of marijuana was for medical purposes while another was a "mortgage helper," Holmquist says.

"In my experience investigating (medical marijuana) grow locations, I have found that there is an overwhelming temptation for ... growers to sell marijuana to supplement their income."

Licences are also used to disguise commercial-scale grow operations, Holmquist says. He investigated a case last year that turned up a chicken barn linked to growing licences. "Twenty-five people, who were not authorized to grow marijuana, were tending to and packaging marijuana for the purpose of trafficking at this (medical marijuana) location."

Organized crime groups are known to target terminal cancer patients, offering large sums to help them enjoy the time they have left, Holmquist says. In return, the patient obtains a marijuana grow licence and makes the criminal their designated grower.

The skunk-like odour of marijuana can help thieves identify growing locations, break in and steal the pot — a crime known as a grow rip.

In B.C., there were four violent grow rips at locations with medical marijuana licences in 2009 and 11 the following year, Holmquist's affidavit says.

Between November 2003 and February last year there were 14 homicides related to grow rips in B.C.'s Lower Mainland.

Growing marijuana in a residence also poses risks from mould, fire and electrical hazards, the affidavit warns.

In a notice of motion seeking the injunction, John Conroy, a lawyer for patients who grow their own marijuana, says they have taken care to create safe, secure production sites.

"They have not had any fires, nor suffered from any toxic mould nor been subjected to any attempted thefts."

One man behind the legal action, Neil Allard of Abbotsford, B.C., says in a court filing it will cost about $200 a day — $72,000 a year — under the proposed new system to buy the marijuana he needs to get relief from symptoms of his serious neuro-immune disorder.

"On the other hand I can produce this herbal medicine for myself for a fraction of that cost and I have been able to produce it and use it effectively maintaining my own quality controls at a cost of approximately $200 to $300 per month."